Hazardous substances, such as toxins and explosives, can be used by terrorists to inflict harm on an unsuspecting public. For example, toxins, such as a pathogenic bacteria or chemical agent, could be included in a letter or package and sent to an unsuspecting victim. In addition to the mail recipient(s), these toxins also are potentially dangerous to workers in the sorting room, as mail sorting equipment can cause the release of certain toxins (e.g., spores of Bacillus anthracis). In some cases, inspecting the mail can be hazardous or damaging to the contents of the packages or letters.
Explosives also pose a significant threat to public safety. When an explosive device is identified, a common method of neutralizing the explosive device is to clear the area and explode it with other explosives. Such an explosion, however, can cause significant property damage. Another option for neutralizing an explosive device is to disassemble it physically, but that can require specialized personnel to interact closely with the explosive device and can put specialized personnel at considerable risk.